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Yes of course. There are techniques which allow astronomers and astrophysicists to calculate these quantities quite efficiently and correctly and it depends on the spectrum, the luminosity and the distance of the star. In fact, from just the luminosity and the distance, one can compute almost everything important about the star including its age, ...


3

Stars don't have a well defined surface. If you plot the density as a function of radial distance then it falls smoothly with distance and in principle is non-zero out to very large distances. A star is basically a ball of (ionised) gas. If you take another example of a ball of gas (well, a spherical shell of gas), i.e. the Earth's atmosphere, it doesn't ...


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Why are Lunar Eclipse more common than Solar Eclipse? They aren't. Lunar eclipses and solar eclipses occur with almost equal frequency. From http://eclipse.gsfc.nasa.gov/eclipse.html and pages within, there were / will be 11898 solar eclipses of all types and 12064 lunar eclipses of all types in the five millennia between 2000 BCE to 3000 CE. Lunar ...


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You have to define what you mean by the "surface". Conventionally the optical photosphere of a star is defined in term of its optical depth to radiation - usually the photosphere is said to be where the optical depth reaches 2/3. Clearly, the gas at this optical depth has a pressure - and this is what one would normally talk about in terms of the surface ...



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